全文获取类型
收费全文 | 381369篇 |
免费 | 34256篇 |
国内免费 | 18792篇 |
专业分类
电工技术 | 64137篇 |
技术理论 | 59篇 |
综合类 | 46754篇 |
化学工业 | 40431篇 |
金属工艺 | 13096篇 |
机械仪表 | 18972篇 |
建筑科学 | 42644篇 |
矿业工程 | 17815篇 |
能源动力 | 16019篇 |
轻工业 | 19762篇 |
水利工程 | 16626篇 |
石油天然气 | 13278篇 |
武器工业 | 3269篇 |
无线电 | 30012篇 |
一般工业技术 | 24467篇 |
冶金工业 | 18116篇 |
原子能技术 | 4887篇 |
自动化技术 | 44073篇 |
出版年
2024年 | 1215篇 |
2023年 | 3833篇 |
2022年 | 7698篇 |
2021年 | 9150篇 |
2020年 | 9720篇 |
2019年 | 8107篇 |
2018年 | 7531篇 |
2017年 | 9631篇 |
2016年 | 11201篇 |
2015年 | 12744篇 |
2014年 | 22762篇 |
2013年 | 20174篇 |
2012年 | 26932篇 |
2011年 | 28889篇 |
2010年 | 22369篇 |
2009年 | 22980篇 |
2008年 | 21749篇 |
2007年 | 27781篇 |
2006年 | 25832篇 |
2005年 | 22087篇 |
2004年 | 18551篇 |
2003年 | 16314篇 |
2002年 | 13297篇 |
2001年 | 11247篇 |
2000年 | 9484篇 |
1999年 | 7582篇 |
1998年 | 5685篇 |
1997年 | 4876篇 |
1996年 | 4480篇 |
1995年 | 3746篇 |
1994年 | 3333篇 |
1993年 | 2406篇 |
1992年 | 2182篇 |
1991年 | 1565篇 |
1990年 | 1345篇 |
1989年 | 1179篇 |
1988年 | 924篇 |
1987年 | 635篇 |
1986年 | 476篇 |
1985年 | 403篇 |
1984年 | 398篇 |
1983年 | 303篇 |
1982年 | 272篇 |
1981年 | 193篇 |
1980年 | 149篇 |
1979年 | 123篇 |
1978年 | 80篇 |
1977年 | 80篇 |
1976年 | 61篇 |
1975年 | 59篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
This paper proposes a method for the coordinated control of power factor by means of a multiagent approach. The proposed multiagent system consists of two types of agent: single feeder agent (F_AG) and bus agent (B_AG). In the proposed system, an F_AG plays as an important role, which decides the power factors of all distributed generators by executing the load flow calculations repeatedly. The voltage control strategies are implemented as the class definition of Java into the system. In order to verify the performance of the proposed method, it has been applied to a typical distribution model system. The simulation results show that the system is able to control very violent fluctuation of the demands and the photovoltaic (PV) generations. 相似文献
42.
43.
Gerd J. Hahn 《国际生产研究杂志》2020,58(5):1425-1441
The Fourth Industrial Revolution – also known as Industry 4.0 (i4.0) – comprises the digitalisation of the industrial sector. This paper uses the theoretical lens of supply chain innovation (SCI) to investigate the implications of i4.0 on supply chain management. For these purposes, the method of structured content analysis is applied to more than 200 use cases of i4.0-enabled SCI introduced by both established and startup companies. i4.0-enabled SCI manifests along three dimensions: process, technology, and business architecture. The key findings of this study can be summarised as follows: first, i4.0-enabled SCI extends the initial focus on productivity improvements in SC processes towards scalability and flexibility. Second, extant i4.0 solutions rely mostly on analytics and smart things while omitting smart people technology and the human-centric approach associated with the i4.0 paradigm. Third, established companies adopt i4.0 merely to sustain their existing business architectures while startup companies radically change their operating models, relying heavily on data analytics and the platform economy. Consequently, established companies pursue a problem-driven, engineering-based approach to SCI while startup companies follow an ‘asset-light’, business-driven approach. Lastly, there are two distinct approaches to digitalising operational SC processes: platform-based crowdsourcing of standard processes and on-demand provision of customised services. 相似文献
44.
价值观的传播是一个缓慢的过程,在当前工业文明向生态文明过渡的时期,如何有效地提升民众的生态意识是值得探讨的问题。以生态审美意识传播为切入点,通过了解国内外主流的室内环境生态评估指标体系的前后变化,总结当前室内环境生态评估的变化趋势及其主要特征;从指标体系的变化中分析生态审美价值观的渗透方式,探讨当代室内环境生态评估对生态审美价值观传播的促进作用。最后,通过实验设定针对室内传统营造技艺应用的评估工具,并且在评估工具的使用过程中展示传播的模式与效用,通过评估反馈再一次验证室内环境生态评估对生态审美价值观的正向传播作用。 相似文献
45.
By leveraging the secret data coding using the remainder storage based exploiting modification direction (RSBEMD), and the pixel change operation recording based on multi-segment left and right histogram shifting, a novel reversible data hiding (RHD) scheme is proposed in this paper. The secret data are first encoded by some specific pixel change operations to the pixels in groups. After that, multi-segment left and right histogram shifting based on threshold manipulation is implemented for recording the pixel change operations. Furthermore, a multiple embedding policy based on chess board prediction (CBP) and threshold manipulation is put forward, and the threshold can be adjusted to achieve adaptive data hiding. Experimental results and analysis show that it is reversible and can achieve good performance in capacity and imperceptibility compared with the existing methods. 相似文献
46.
Daniela Fogli Antonio Piccinno Stefan Carmien Gerhard Fischer 《Behaviour & Information Technology》2020,39(1):27-46
ABSTRACTThe digital age of the future is ‘not out there to be discovered’, but it needs to be ‘designed’. The design challenge has to address questions about how we want to live, work, and learn (as individuals and as communities) and what we value and appreciate, e.g.: reflecting on quality of life and creating inclusive societies. An overriding design trade-off for the digital age is whether new developments will increase the digital divide or will create more inclusive societies. Sustaining inclusive societies means allowing people of all ages and all abilities to exploit information technologies for personally meaningful activities. Meta-design fosters the design of socio-technical environments that end-user developers can modify and evolve at use time to improve their quality of life and favour their inclusion in the society. This paper describes three case studies in the domain of assistive technologies in which end users themselves cannot act as end-user developers, but someone else (e.g.: a caregiver or a clinician) must accept this role requiring multi-tiered architectures. The design trade-offs and requirements for meta-design identified in the context of the case studies and other researchers’ projects are described to inform the development of future socio-technical environments focused on social inclusion. 相似文献
47.
Yasoub Eghbali Mahmoud Ferdosizade Naeiny 《International Journal of Communication Systems》2020,33(14)
In this paper, an off‐grid direction of arrival (DoA) estimation method is proposed for wideband signals. This method is based on the sparse representation (SR) of the array covariance matrix. Similar to the time domain DoA estimation methods, the correlation function of the sources was assumed to be the same and known. A new measurement vector is obtained using the lower‐left triangular elements of the covariance matrix. The DoAs are estimated by quantizing the entire range of continuous angle space into discrete grid points. However, the exact DoAs may be located between two grid points; therefore, this estimation has errors. The accuracy of DoA estimation is improved by the minimization of the difference between the new measurement vector and its estimated values. Simulation results revealed that the proposed method can enhance the DoA estimation accuracy of wideband signals. 相似文献
48.
49.
50.